FL_F150

Thought i'd run this by you guys... numerous things can cause the problem I am having.


Three weeks ago, my truck died at a stop light, started right back up, runs fine.
Over the past two weeks it kept progressing to almost every stop light, unless I two footed it and kept the idle above 1000.
It started by giving the lean on bank one and two codes (P0171,P0174)
I started by cleaning the MAF sensor and temp sensor in the air inlet.
I then changed the air filter and fuel filter.
Next I moved on to the AIC....
Then replaced about 90 percent of my vacuums lines (I have a PCV line on order).
The engine now runs great for about 2 minutes until it warms up, then idle gets really rough and eventually it dies.
I still have to check fuel pressure, but it runs really great after I put my foot in it and get it above 1000 rpm.
I hate having to replace stuff not knowing where to start.... I have read many a post on the problem and each posts says to start somewhere different.
I'll keep posting until I solve it.....

FL_F150

So I stuck my ODB II tester on it.... no codes....still idles like crap
At Live DATA
Idle 660rpm
Short term fuel trim 0.8%
Long term fuel trim -0.0%


1500 rpm
Short term fuel trim 25.5%
Long term fuel trim 12.5%


1865 rpm (closest I could keep it close to 2k)
Short term fuel trim 14.8%
Long term fuel trim 12.5%


So.... is it my fuel pump? not sure...I am taking it to O'Riellys to see if they have a fuel pressure guage I can use.

Jbrew

660 is too low, should be 730.

1. Fuel first (always)
2. IAC (non responsive)
3. EGR (poppet stuck open)
4. Cats (plugged or partial)

Jefk

clean your sensors, that was my problem on my old truck because it wasn't tracking all the air coming into the motor so its overcompensating with gas, it ended up being the MAF/MAP sensor that ended up needing replacement. after a couple more weeks.

Jbrew

What are you quoting me for ?

Jefk

it appears your the one quoting now lol

FL_F150

I cleaned the sensors.... was the first thing I did...
The 660 was because of the crappy idle going on.....


I have 32 pounds of fuel pressure.... from what I hear for a 5.4 that is low but still in the good range....


I am awaiting my pcv line....it is on order...


Seems like everything I do makes it worse....

Ringleader

Sub'd.
Mine's doing exactly what yours is. I'm tired of chasing it.

tbzep

If none of the above pan out, look at your COP's.
I had COP issues that caused my 2000 5.4 to idle rough with just one going bad. If two or three got weak at the same time, I'm sure it would have died at idle. It ran fine with throttle, but I eventually started getting heavy shaking when going into overdrive. It was due to the COP not being able to ignite the mixture when the fuel map called for it to be leaned out. It never threw a code until I got to the heavy shaking stage.

FL_F150

Mine threw a "b" and "e" COP code last winter, but straightened out during the summer...
My tester does not give cylinder numbers (Chinese) but alpha's so I guess it is 2 and 5 ?
I have a couple of COP's sitting on a shelf just in case.... no codes have been thrown since I changed the IAC valve, the lean bank 1 & 2 disappeared.